Hygrometer



Sept. 6, 1949. F. B. NEWELL EI'AL 2,431,332

HYGROMETER Filed Dec. 10, 1947- FIG. 3

INVENTOR. F.B. NEWELL v.5. MATNER Patented Sept. 6, 1949 HYGROMETER Floyd B. Newell and Vincent E. Matner, Rochester, N. Y., assignors to Taylor Instrument Companies, Rochester, N. Y., a corporation of New York Application December 10, 1947, Serial No. 790,770

6 Claims. 1

This invention relates to an arrangement for supplying moisture to an element such as the wet bulb of a wet and dry bulb thermometer unit.

In accordance with one method of calculating relative humidity, it is common practice to use a dry bulb thermometer and in addition a socalled wet bulb thermometer to obtain data from which the relative humidity can be determined. In the past much difiiculty has been encountered in keeping the wick of the wet bulb thermometer properly moistened.

The present invention is particularly directed to a novel arrangement for supplying water in small uniform quantities to the Wick of a wet bulb thermometer so that a higher degree of accuracy in measuring the wet bulb thermometer temperature can be achieved.

The various features and advantages of the invention will appear from the detailed description and claims when taken with the drawings in which:

Fig. 1 is a front elevation of a wet and dry bulb thermometer unit incorporating the present invention, a portion of the casing of the unit being broken away and the indicating portions of the two thermometers of the unit being omitted;

Figs. 2 and 3 are respectively, enlarged detailed side and front views, partially in section, of the water supplying mechanism forming a part of the unit; and

Fig. 4 is a sectional View taken substantially in the line 3-3 of Fig. 1 showing the mounting of the wick for supplying moisture to the wet bulb.

The wet bulb and dry bulb thermometer unit of the present invention includes a compartment defined by a casing 5 which is closed except for an inlet opening into a duct 6 and a lateral opening near its bottom communicating through an exhaust fan 1, with outlet duct 8. The duct 6 leads to a room or chamber, the humidity of which is to be determined. This fan draws the sample air through the duct 6 and through the casing 5 for discharge through the outlet pipe 8. At the right-hand portion of the compartment (Fig. 1) there is mounted the vertically extending dry bulb 9 of a dry bulb thermometer which is herein shown as being of the tube system type. This bulb 9 which is preferably in the form of a coiled capillary tube, sealed at its upper end, communicates through the capillary tube It] with the indicating portion (not shown) of the dry bulb thermometer. It will be understood that this dry bulb thermometer indicates the temperature of the air sample drawn into the compartment by the fan 1.

The left-hand wall ll of the compartment has mounted therein the wet bulb [2 of a wet bulb thermometer of the tube system type. In accordance with the usual practice, this bulb is made of metal such as steel and communicates through a capillary tube 14 exterior of the casing and leading to the indicating mechanism (herein omitted) of the wet bulb thermometer. In order to determine the wet bulb temperature, as a result of the evaporation of the water applied to the bulb of this thermometer, this bulb is provided with a wick I5 made of suitable wicking. The lower end of this wicking is wrapped snugly around the bulb and is attached to the main body thereof. The upper end of the wicking is likewise wrapped around a cylinder I! having its right end (Figs. 1 and 3) closed and having its open left end attached to the margin of the casing around an opening therein. The wicking after being wrapped around this cylinder is attached to the main body thereof, thereby providing a V-shaped portion l8 in the wick into which the water can drop as will be hereinafter set forth. It will be noted that the bottom of the tube is perforated at l9 so that water therein can drip into the V-shaped portion l8 of the wick directly beneath the tube.

In accordance with the present invention, the cylinder I 1 is supplied with a uniform quantity of water. The mechanism for effecting this result comprises a reservoir I3 supported on the side wall of the casing which reservoir is supplied continuously with water through the supply pipe 20. The reservoir is also provided with an overflow pipe 2! so that a fixed level of water is maintained in the reservoir. The water in the reservoir is intermittently supplied to the cylinder I! by a pump mechanism comprising a scoop preferably in the form of a curved or Bourdon tube 22, the outer, open end of which is adapted to dip into the water in the reservoir 13. The inner open end of this tube 22 is fixed at right angles to and communicates with a hollow pipe 23 which extends horizontally for a substantial distance into the previously mentioned hollow cylinder 11. The pipe 23 and spiral tube 22 are rotated by a shaft 24 coupled thereto at 25. This shaft is driven at a uniform rate by a suitable motor 26 such as a synchronous motor.

Briefly the operation of the mechanism is as follows: The supply of water to the reservoir I3 is turned on, after which the motor 26 and exhaust fan 1 are started. As the motor shaft 24 rotates, the spiral tube 22 is likewise rotated and intermittently dips its outer end into the temperature of the water will first approach that of the room as it passes through the constant level reservoir I3, the pump mechanism including spiral tube 22, and the tube 23. The temperature of the pumped water will then become cooled by evaporation as it passes down the wick and approaches the wet bulb l2. The rate at which the water is supplied (which is dependent upon the height of the water level in the reservoir l3 and the speed of rotation of the spiral tube 22, as well as the dimensions of the tube) is only enough to allow for a small excess to drip from the wick at the wet bulb end thereof and flow away to a drain 2?, (which, I believe, has not been mentioned). A baflle 28 is mounted in the compartment so that the air sample applied to the dry bulb 9 will not be modified by moisture derived from the wick 15.

What We claim is:

1. In combination with the wet bulb of a hygrometer, a device for supplying moisture to said bulb comprising a reservoir provided with means for maintaining a uniform level of liquid therein, mechanism including a scoop arranged when operated to dip periodically a uniform depth into said liquid and to elevate as well as discharge a uniform amount of said liquid, means for operating said mechanism at a uniform rate, and means for applying the discharged liquid to said bulb.

2. In combination with the wet bulb of a hygrometer, a wick engaging said bulb, a device for supplying moisture to said wick, comprising a reservoir provided with means for maintaining a uniform level of liquid therein, mechanism including a scoop arranged when operated to dip periodically a uniform depth into said liquid and to elevate as well as discharge a uniform amount of said liquid on said wick, and means for operating said mechanism at a uniform rate.

3. In combination with the wet bulb of a hygrometer, said bulb being encircled by an upwardly extending wick, a device for supplying moisture to said wick, comprising a reservoir provided with means for maintaining a uniform level of liquid therein, mechanism including a scoop arranged when operated to dip periodically a'uniform depth into said liquid and to elevate as well as discharge a uniform amount of said 4 liquid on an upper portion of said wick remote from said bulb, and means for operating said mechanism at a uniform rate.

4. In combination with the wet bulb of a hygrometer, a wick engaging said bulb, mechanism for supplying moisture to said wick comprising a reservoir provided with means for maintaining a uniform level of liquid therein, a scoop in the form of a curved tube mounted to rotate on a horizontal axis above the level of said liquid, one end of said tube extending away from said axis in a direction to dip periodically a uniform depth into said liquid as the scoop is rotated, means for delivering the liquid in said scoop to said wick, and means for rotating said scoop at a uniform rate.

5. In combinationwith the wet bulb of a hygrometer, mechanism for supplying moisture to said bulb comprising a reservoir provided with means for maintaining a uniform level of liquid therein, a scoop in the form of a curved tube mounted to rotate on a horizontal axis above the level of said liquid, one end of said tube extending away from said axis in a direction to dip a uniform depth into said liquid as the scoop is rotated, means for rotating said scoop at a uniform rate, and means for delivering the liquid in said scoop to said wet bulb.

6. In combination with the wet bulb of a hygrometer mechanism for supplying moisture to said bulb comprising a reservoir provided with means for maintaining a uniform level of liquid therein, a scoop in the form of a Bourdon tube having inner and outer open ends, a pipe fixed to and communicating with the inner end of said tube and mounted to rotate on a horizontal axis above the level of said liquid, the outer end of said tube extending away from said axis in a direction to clip a uniform depth into said liquid as the scoop is rotated, whereby liquid is delivered into said pipe, means for rotating said tube and pipe at a uniform rate, and means for delivering the liquid in said pipe to said bulb.

FLOYD B. NEWELL. VINCENT E. MATNER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 355,329 Le Blanc Jan. 4, 1887 863,250 Abbe Aug. 13, 1907 1,308,930 Carrier July 8, 1919 1,481,251 Braemer Jan. 22, 1924 1,553,962 Rhoads Sept. 15, 1925 

